We analyze the interaction between a free electron and an ensemble of identical optical emitters. The mutual coherence and correlations between the emitters can enhance the interaction with each electron and become imprinted on its energy spectrum. We present schemes by which such collective interactions can be realized. As a possible application, we investigate free-electron interactions with superradiant systems, showing how electrons can probe the ultrafast population dynamics of superradiance.
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http://dx.doi.org/10.1021/acs.nanolett.2c03396 | DOI Listing |
Phys Rev Lett
November 2024
Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
Bilayer materials may support interlayer excitons comprised of electrons in one layer and holes in the other. In experiments, a nonzero exciton density is typically sustained by a bias chemical potential, implemented either by optical pumping or by electrical contacts connected to the two layers. We show that if charge can tunnel between the layers, the chemical potential bias means that an exciton condensate is in the dynamical regime of ac Josephson effect.
View Article and Find Full Text PDFRep Prog Phys
December 2024
School of Electrical Engineering-Physical Electronics, Center of Light-Matter Interaction, Tel Aviv University, Ramat Aviv 69978, Israel.
It has been shown that the spontaneous emission rate of photons by free electrons, unlike stimulated emission, is independent of the shape or modulation of the quantum electron wavefunction (QEW). Nevertheless, here we show that the quantum state of the emitted photons is non-classical and does depend on the QEW shape. This non-classicality originates from the shape dependent off-diagonal terms of the photon density matrix.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2024
Dipartimento di Fisica e Geologia, Università di Perugia, Perugia I-06123, Italy.
We study the Thomson scattering from highly oriented pyrolitic graphite excited by the extreme ultraviolet, coherent pulses of FERMI free electron laser (FEL). An apparent nonlinear behavior is observed and fully described in terms of the coherent nature of both exciting FEL beam and scattered radiation, producing an intensity-dependent enhancement of the Thomson scattering cross-section. The process resembles Dicke's superradiant phenomenon and is thus interpreted as the observation of superradiant Thomson scattering.
View Article and Find Full Text PDFJ Chem Phys
January 2024
School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa 923-1292, Japan.
We developed a spectroscopic method for directly obtaining the spectra of electromagnetic (EM) enhancement of plasmonic hotspots (HSs). The method was applied to one-dimensional (1D) HSs generated between silver nanowire (NW) dimers. The EM enhancement spectra were derived by dividing the spectra of surface-enhanced fluorescence (SEF) from single NW dimers with SEF obtained from large nanoparticle aggregates, where aggregate-by-aggregate variations in the SEF spectra were averaged out.
View Article and Find Full Text PDFNaturally down-chirped superradiance pulses, with mirco-pulse energy, peak wavelength, and micropulse duration of 40 µJ, 8.7 μm, and 5.1 optical cycles, respectively, emitted from a free-electron laser (FEL) oscillator were nonlinearly compressed down to 3.
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